What We Repair on Combi Boilers
No heat and no hot water simultaneously
No heat but hot water working (or vice versa)
Ignition failure and lockout fault codes
Low pressure / pressure loss diagnosis
Diverter valve failure — stuck in heat or DHW mode
Heat exchanger scaling and blockage
Condensate pipe blockage or freeze
Gas valve replacement
Pump failure and circulation issues
Control board and sensor replacement
Flue and venting inspection
Navien, NTI, Viessmann, Weil-McLain, IBC
Boiler Not Working Right Now?
Call directly for same-day emergency response across York Region. We carry common parts on the truck.
📞 647-699-2474Our Repair Process
- Call or submit a quote — we take your info, ask the right questions (brand, error code if visible, symptoms), and give you an ETA.
- Arrive with parts — we stock the most common combi boiler parts. For Navien and NTI especially, we carry ignitors, sensors, diverter valves, and PCBs.
- Full diagnostic — we don't guess. We test gas pressure, ignition sequence, diverter operation, heat exchanger output, and DHW flow before touching anything.
- Repair and test — once the fault is confirmed, we repair it, reset the system, and run a full heat and hot water test cycle before leaving.
- Plain-English summary — we explain exactly what failed, why, and what to watch for going forward. No technical jargon you don't need.
Common Questions
Almost always the diverter valve. On a combi boiler, a single diverter valve switches the system between space heating mode and domestic hot water mode. When it fails (usually seized in the heating position), the boiler heats your radiators fine but domestic hot water gets little or no heat. This is a common repair on all combi brands — Navien, NTI, Viessmann — and usually a same-visit fix.
Don't reset it more than once. Write down the code (e.g. E003, E012, E110) and call us. Navien error codes are specific — E003 is ignition failure, E012 is flame loss, E110 is high limit. Knowing the code means we arrive with the right parts. Repeated resets can mask intermittent faults and make diagnosis harder.
Three common causes: a slow leak somewhere in the system (check under radiators and at the boiler connections), a failing pressure relief valve that's weeping, or a waterlogged expansion vessel that needs recharging or replacing. We test all three during the service call. If the system keeps losing pressure after a refill, don't keep topping it up — the root cause needs to be found.
Yes — this is very common in Ontario winters. The condensate pipe is the plastic pipe that drains acidic condensate from a high-efficiency boiler to a drain. When it freezes, the boiler shuts down on a fault. We thaw the pipe, check the routing and insulation, and reposition or insulate it to prevent recurrence. It's a quick fix — and preventable with proper pipe routing.
Most common repairs — diverter valve, ignitor, pressure relief valve, sensor replacement — take 1–2 hours including diagnosis and testing. Heat exchanger descaling and pump replacement can take 2–3 hours. We give you a realistic estimate before starting work.
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G1 licensed, Navien and NTI certified. York Region's owner-operated boiler specialist — the tech who answers is the tech who shows up.
- ✓ G1 Licensed — all gas boiler work
- ✓ Navien & NTI factory certified
- ✓ All brands and boiler types
- ✓ Same-day for emergencies
- ✓ Upfront pricing — no surprises
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Free estimate — York Region